John, what year is the car your restoring? Is it the 77? From 71 to 76, I believe the interior color on a BRG car was Autumn Leaf. I'm not sure if there was a definite year or years for a definite interior/exterior color match. My BRG 72 had an Autumn Leaf interior. Sort of a brown rubber on the door sills and the carpet was so faded, it was hard to determine the actual color. Looked like it might have been tan?
I've been told that in the past, Autumn Leaf was one of the hardest interior colors to get, but Moss now sells it. Even though I had my 72 painted Flame Red, I put a biscuit interior back in it and it looks great. An friend of mine in Columbia, SC has a 79 BRG with a tan interior and it also looks great. PJ